This 14-year-old white male first experienced mild pain in the left knee after playing baseball, approximately two months prior to admission. The pain persisted in an intermittent fashion, and was described as being somewhat worse at night. Approximately two weeks prior to admission, the pain increased significantly and was accompanied by marked swelling and loss of considerable motion of the knee joint. These symptoms were accompanied by a history of decreased appetite, lethargy, and a 10-pound weight loss. On physical examination, the left knee was enlarged diffusely, firm, and non-tender. Following biopsy, the patient was subjected to surgical removal of the distal femur and knee with placement of a prosthetic knee joint and bone grafts.
The distal diaphysis of the femur and adjacent soft tissues were involved in a 15 x 10 x 10-cm mass. The cut surface of the mass was fleshy white, with focal areas of hemorrhage.
Osteosarcoma is the most common primary malignant tumor of bone exclusive of myeloma and lymphoma and accounts for approximately 20% of primary bone cancers. Males are more commonly affected than females (1.6:1). Osteosarcoma occurs in all age groups but has a bimodal age distribution. Approximately 75% occur in patients younger than 20 years of age. The smaller second peak (secondary osteosarcoma) occurs in elderly patients who suffer from conditions known to be associated with the development of osteosarcoma (Paget’s disease, bone infarcts, and prior irradiation).
Osteosarcomas usually arise in the metaphyseal region of the long bones of the extremities, and almost 60% occur about the knee. The location, in descending order of frequency, is distal femur, proximal tibia, proximal humerus, and proximal femur.
Gene mutations are fundamental to the development of osteosarcoma. Patients with hereditary retinoblastomas have a several hundred-fold greater risk of developing osteosarcoma. Mutations in the p53 suppressor gene (Li-Fraumeni syndrome) has been implicated in the development of most nonhereditary osteosarcomas as well as many other types of cancer. Interestingly, many osteosarcomas develop at sites of greatest bone growth where bone cell mitotic activity is at its peak--e.g., the base of the femoral growth plate where primary spongiosa is being formed and in Pagetic bone with its frenzy of bone formation and resorption.
Osteosarcomas are aggressive neoplasms that spread through the bloodstream, and at the time of diagnosis, approximately 20% of patients have demonstrable pulmonary metastases. In those who die of the neoplasm, 90% have metastases to the lungs, bones, brain, and elsewhere. With current treatment regimens the long-term survival rate has been increased to approximately 60% from the historic controls of 25%.
- Wittig JC, Bickels J, Priebat D, Jelinek J, Kellar-Graney K, Shmookler B, Malawer MM. Osteosarcoma: a multidisciplinary approach to diagnosis and treatment. Am Fam Physician 2002 Mar 15;65(6):1123-32.
- Miller SL, Hoffer FA. Malignant and benign bone tumors. Radiol Clin North Am 2001 Jul;39(4):673-99.
The normal fibrinogen level is 184 to 412 mg/dL.